Effects of Bupropion in Depression

This study will investigate the role of dopaminergic neural systems in the symptoms and treatment of depression. 40 patients who meet DSM-IV criteria for a diagnosis of depression will be compared to a matched sample of healthy controls. The depressed group will receive open label treatment with Bupropion MR (150mg bd) for 6 weeks. The control group will receive no treatment. All participants will be assessed before treatment, after 2 weeks treatment and at 6 weeks treatment. The outcomes assessed will be 1) fMRI estimates of neural response to reward to emotionally valenced stimuli (1st and 2nd assessments), 2) computer based measures of emotional processing (all assessments) and 3) standardised questionnaire measures of depressive symptoms (all assessments). The primary study hypothesis is that altering central dopamine using Bupropion will lead to altered neural responses to rewarding stimuli in the depressed patients (i.e. comparing fMRI outcomes between assessment visits 1 and 2). A secondary hypothesis is that this neural change will predict subsequent symptom response to the bupropion (i.e. comparing symptom scores between assessment visits 1 and 3), Lastly, the study will test the hypothesis that baseline differences in reward circuitry will be particularly associated with symptoms of anhedonia (the inability to experience pleasure).